In micro-electromechanical (MEMS) device gyroscopes, proof masses are oscillated to vibrate at a resonance frequency. The oscillations are locked to the resonance frequency by a control loop that senses motion of the proof masses and provides a feedback signal to a set of drive electrodes. One challenge in working with MEMS gyroscopes is developing devices that have fast start times. That is, when a MEMS gyroscope is first started, the proof masses are not operating and therefore there is no signal into the control loop that regulates the drive electrodes. But as the proof masses continue to be driven, a small signal will begin to develop. During the initial stages of startup, this signal is very small in magnitude and easily masked by higher magnitude noise on the pickup lines that senses motion of the proof masses. This noise on the pickup lines enters the control loop and results in an erroneous feedback signal to the drive electrodes, increasing the amount of time necessary for the proof masses to reach their operating resonance frequency.
One significant source of noise which can masks the true proof mass motion signals is parasitic coupling between circuit board traces carrying the drive signals to the drive electrodes and the pickup traces carrying sensed motion signals to the control loop. Modeling and simulation of circuit board layouts can go a long way towards designing circuit boards for MEMS devices that either reduce, or at least balance, coupling between device components. However, such models for MEMS devices are inherently limited in their ability to accurately predict coupling in fabricated MEMS devices. Further, device fabrication vendors are inherently limited to manufacturing tolerances which can introduce unknowns not easily accounted for through prefabrication modeling.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for systems and methods for improving MEMS gyroscope start time delays.